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H G Pickles

Publications and source records attributed to H G Pickles.

6 recordsLinked to original sources
PubMed1979

Presynaptic gamma-aminobutyric acid responses in the olfactory cortex.

1. Potential changes were recorded from the lateral olfactory tract in slices of rat olfactory cortex in vitro at room temperature. 2. Superfused gamma-aminobutyric acid (GABA) usually produced dose-related depolarization of the lateral olfactory tract. Muscimol and 3-aminopropanesulphonic acid appeared more potent depolarizing agents than GABA, and glycine and taurine appeared less potent. Carbachol and glutamate were virtually ineffective. 3. The GABA responses were at least partially Cl- dependent. 4. (+)-Bicuculline and higher concentrations of strychnine antagonized the GABA but not the glycine-induced depolarizations. Paradoxically, responses to high doses of GABA were sometimes potentiated by both bicuculline and strychnine. 5. It is suggested that GABA receptors could occur as widely on nerve terminals as they do postsynaptically in the CNS, where GABA could be involved in the modulation of transmitter output.

Animals↗
PubMed1978

Field potentials, inhibition and the effect of pentobarbitone in the rat olfactory cortex slice.

1. Field potentials were evoked in slices of rat olfactory cortex by stimulating the lateral olfactory tract. In addition to previously described components of the wave-form, a further distinct surface-negative potential of low amplitude and long duration (I-wave) has been described. 2. Pentobarbitone, at concentrations of 10(-5) M and above, markedly enhanced enhanced the amplitude and duration of the I-wave with only minimal effect on other components of the field potential. 3. The I-wave was reversibly reduced by the GABA antagonists bicuculline and picrotoxin and was also attenuated at rapid rates of stimulation. Low chloride medium usually caused a transient increase in amplitude of the I-wave followed by a gradual reduction, suggesting that a chloride-mediated depolarization was involved. 4. Evoked inhibition, which was most probably post-synaptic, occurred in parallel with the I-wave. This was monitored as a suppression of, or increase in latency of the population spike evoked by a second stimulus at appropriate intervals after the first. Pentobarbitone substantially increased the duration of the post-synpatic inhibition, without obvious changes in the presynaptic inhibitory phenomenon associated with antidromic firing in the lateral olfactory tract. 5. It is proposed that the I-wave is the field potential representation of a population depolarizing i.p.s.p. and that the main action of pentobarbitone is to enhance this inhibition.

Action Potentials↗
PubMed1976

Possible presynaptic inhibition in rat olfactory cortex.

1. Field potentials were evoked from rat olfactory cortex slices in vitro at room temperature by lateral olfactory tract stimulation. At very slow stimulation rates (less than 0-1 Hz) a delayed negative wave (late N-wave) was found to follow the first negative wave (N-wave). This late N-wave started 30 msec after the stimulus and lasted for 50-150 msec. 2. Low Ca2+/high Mg2+ medium abolished the late N-wave more rapidly than the N-wave, suggesting a possible multisynaptic origin. 3. The GABA antagonist bicuculline (10(-6) M) abolished the late N-wave without affecting the N-wave. 4. During the late N-wave, both the tract action potential and the N-wave to a second stimulus were reduced. This was attributed, at least in part, to collision with antidromic action potentials which could be detected during the late N-wave. 5. These findings are discussed in terms of a possible presynaptic depolarizing action of a GABA-like transmitter giving rise to presynaptic inhibition and the late N-wave.

Animals↗